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<!DOCTYPE refentry [ <!ENTITY % mathent SYSTEM "math.ent"> %mathent; ]>
<!-- Converted by db4-upgrade version 1.1 -->
<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="textureGrad">
<info>
<copyright>
<year>2011-2014</year>
<holder>Khronos Group</holder>
</copyright>
</info>
<refmeta>
<refentrytitle>textureGrad</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>textureGrad</refname>
<refpurpose>perform a texture lookup with explicit gradients</refpurpose>
</refnamediv>
<refsynopsisdiv><title>Declaration</title>
<funcsynopsis>
<funcprototype>
<funcdef>gvec4 <function>textureGrad</function></funcdef>
<paramdef>gsampler1D <parameter>sampler</parameter></paramdef>
<paramdef>float <parameter>P</parameter></paramdef>
<paramdef>float <parameter>dPdx</parameter></paramdef>
<paramdef>float <parameter>dPdy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>gvec4 <function>textureGrad</function></funcdef>
<paramdef>gsampler2D <parameter>sampler</parameter></paramdef>
<paramdef>vec2 <parameter>P</parameter></paramdef>
<paramdef>vec2 <parameter>dPdx</parameter></paramdef>
<paramdef>vec2 <parameter>dPdy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>gvec4 <function>textureGrad</function></funcdef>
<paramdef>gsampler3D <parameter>sampler</parameter></paramdef>
<paramdef>vec3 <parameter>P</parameter></paramdef>
<paramdef>vec3 <parameter>dPdx</parameter></paramdef>
<paramdef>vec3 <parameter>dPdy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>gvec4 <function>textureGrad</function></funcdef>
<paramdef>gsamplerCube <parameter>sampler</parameter></paramdef>
<paramdef>vec3 <parameter>P</parameter></paramdef>
<paramdef>vec3 <parameter>dPdx</parameter></paramdef>
<paramdef>vec3 <parameter>dPdy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>gvec4 <function>textureGrad</function></funcdef>
<paramdef>gsampler2DRect <parameter>sampler</parameter></paramdef>
<paramdef>vec2 <parameter>P</parameter></paramdef>
<paramdef>vec2 <parameter>dPdx</parameter></paramdef>
<paramdef>vec2 <parameter>dPdy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>float <function>textureGrad</function></funcdef>
<paramdef>gsampler2DRectShadow <parameter>sampler</parameter></paramdef>
<paramdef>vec2 <parameter>P</parameter></paramdef>
<paramdef>vec2 <parameter>dPdx</parameter></paramdef>
<paramdef>vec2 <parameter>dPdy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>float <function>textureGrad</function></funcdef>
<paramdef>sampler1DShadow <parameter>sampler</parameter></paramdef>
<paramdef>vec3 <parameter>P</parameter></paramdef>
<paramdef>float <parameter>dPdx</parameter></paramdef>
<paramdef>float <parameter>dPdy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>float <function>textureGrad</function></funcdef>
<paramdef>sampler2DShadow <parameter>sampler</parameter></paramdef>
<paramdef>vec3 <parameter>P</parameter></paramdef>
<paramdef>vec2 <parameter>dPdx</parameter></paramdef>
<paramdef>vec2 <parameter>dPdy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>gvec4 <function>textureGrad</function></funcdef>
<paramdef>gsampler1DArray <parameter>sampler</parameter></paramdef>
<paramdef>vec2 <parameter>P</parameter></paramdef>
<paramdef>float <parameter>dPdx</parameter></paramdef>
<paramdef>float <parameter>dPdy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>gvec4 <function>textureGrad</function></funcdef>
<paramdef>gsampler2DArray <parameter>sampler</parameter></paramdef>
<paramdef>vec3 <parameter>P</parameter></paramdef>
<paramdef>vec2 <parameter>dPdx</parameter></paramdef>
<paramdef>vec2 <parameter>dPdy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>float <function>textureGrad</function></funcdef>
<paramdef>sampler1DArrayShadow <parameter>sampler</parameter></paramdef>
<paramdef>vec3 <parameter>P</parameter></paramdef>
<paramdef>float <parameter>dPdx</parameter></paramdef>
<paramdef>float <parameter>dPdy</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>gvec4 <function>textureGrad</function></funcdef>
<paramdef>gsamplerCubeArray <parameter>sampler</parameter></paramdef>
<paramdef>vec4 <parameter>P</parameter></paramdef>
<paramdef>vec3 <parameter>dPdx</parameter></paramdef>
<paramdef>vec3 <parameter>dPdy</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 xml:id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>sampler</parameter></term>
<listitem>
<para>
Specifies the sampler to which the texture from which texels will be retrieved is bound.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>P</parameter></term>
<listitem>
<para>
Specifies the texture coordinates at which texture will be sampled.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>dPdx</parameter></term>
<listitem>
<para>
Specifies the partial derivative of <parameter>P</parameter> with respect to window x.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>dPdy</parameter></term>
<listitem>
<para>
Specifies the partial derivative of <parameter>P</parameter> with respect to window y.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 xml:id="description"><title>Description</title>
<para>
<function>textureGrad</function> performs a texture lookup at coordinate <parameter>P</parameter> from the
texture bound to <parameter>sampler</parameter> with explicit texture coordinate gradiends as specified in
<parameter>dPdx</parameter> and <parameter>dPdy</parameter>. Set:
</para>
<para>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<mml:mfrac>
<mml:mi>δs</mml:mi>
<mml:mi>δx</mml:mi>
</mml:mfrac>
<mml:mo>=</mml:mo>
<mml:mfrac>
<mml:mi>δP</mml:mi>
<mml:mi>δx</mml:mi>
</mml:mfrac>
<mml:mi> for a 1D texture, </mml:mi>
<mml:mfrac>
<mml:mi>δP.s</mml:mi>
<mml:mi>δx</mml:mi>
</mml:mfrac>
<mml:mi> otherwise</mml:mi>
</mml:math></inlineequation>
</para>
<para>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<mml:mfrac>
<mml:mi>δs</mml:mi>
<mml:mi>δy</mml:mi>
</mml:mfrac>
<mml:mo>=</mml:mo>
<mml:mfrac>
<mml:mi>δP</mml:mi>
<mml:mi>δy</mml:mi>
</mml:mfrac>
<mml:mi> for a 1D texture, </mml:mi>
<mml:mfrac>
<mml:mi>δP.s</mml:mi>
<mml:mi>δy</mml:mi>
</mml:mfrac>
<mml:mi> otherwise</mml:mi>
</mml:math></inlineequation>
</para>
<para>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<mml:mfrac>
<mml:mi>δt</mml:mi>
<mml:mi>δx</mml:mi>
</mml:mfrac>
<mml:mo>=</mml:mo>
<mml:mn>0.0</mml:mn>
<mml:mi> for a 1D texture, </mml:mi>
<mml:mfrac>
<mml:mi>δP.t</mml:mi>
<mml:mi>δx</mml:mi>
</mml:mfrac>
<mml:mi> otherwise</mml:mi>
</mml:math></inlineequation>
</para>
<para>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<mml:mfrac>
<mml:mi>δt</mml:mi>
<mml:mi>δy</mml:mi>
</mml:mfrac>
<mml:mo>=</mml:mo>
<mml:mn>0.0</mml:mn>
<mml:mi> for a 1D texture, </mml:mi>
<mml:mfrac>
<mml:mi>δP.t</mml:mi>
<mml:mi>δy</mml:mi>
</mml:mfrac>
<mml:mi> otherwise</mml:mi>
</mml:math></inlineequation>
</para>
<para>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<mml:mfrac>
<mml:mi>δr</mml:mi>
<mml:mi>δx</mml:mi>
</mml:mfrac>
<mml:mo>=</mml:mo>
<mml:mn>0.0</mml:mn>
<mml:mi> for a 1D or 2D texture, </mml:mi>
<mml:mfrac>
<mml:mi>δP.p</mml:mi>
<mml:mi>δx</mml:mi>
</mml:mfrac>
<mml:mi> otherwise</mml:mi>
</mml:math></inlineequation>
</para>
<para>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<mml:mfrac>
<mml:mi>δr</mml:mi>
<mml:mi>δy</mml:mi>
</mml:mfrac>
<mml:mo>=</mml:mo>
<mml:mn>0.0</mml:mn>
<mml:mi> for a 1D or 2D texture, </mml:mi>
<mml:mfrac>
<mml:mi>δP.p</mml:mi>
<mml:mi>δy</mml:mi>
</mml:mfrac>
<mml:mi> otherwise</mml:mi>
</mml:math></inlineequation>
</para>
<para>
For the cube version, the partial derivatives of <parameter>P</parameter> are assumed to be
in the coordinate system used before texture coordinates are projected onto the appropriate
cube face.
</para>
</refsect1>
<refsect1 xml:id="versions"><title>Version Support</title>
<informaltable>
<tgroup cols="13" align="left">
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="funchead.xml" xpointer="xpointer(/*/*)"/>
<tbody>
<row>
<entry>textureGrad</entry>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="version.xml" xpointer="xpointer(/*/*[@role='13']/*)"/>
</row>
<row>
<entry>textureGrad (gsampler2DRect{Shadow})</entry>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="version.xml" xpointer="xpointer(/*/*[@role='14']/*)"/>
</row>
<row>
<entry>textureGrad (gsamplerCubeArray)</entry>
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="version.xml" xpointer="xpointer(/*/*[@role='40']/*)"/>
</row>
</tbody>
</tgroup>
</informaltable>
</refsect1>
<refsect1 xml:id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>texelFetch</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>texelFetchOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>texture</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureGather</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureGatherOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureGatherOffsets</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureGradOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureLod</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureLodOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureProj</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureProjGrad</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureProjGradOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureProjLod</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureProjLodOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureProjOffset</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureQueryLod</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>textureSize</refentrytitle></citerefentry>
</para>
</refsect1>
<refsect1 xml:id="Copyright"><title>Copyright</title>
<para>
Copyright <trademark class="copyright"/> 2011-2014 Khronos Group.
This material may be distributed subject to the terms and conditions set forth in
the Open Publication License, v 1.0, 8 June 1999.
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://opencontent.org/openpub/">http://opencontent.org/openpub/</link>.
</para>
</refsect1>
</refentry>
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